Use this URL to cite or link to this record in EThOS:
Title: Numerical modelling of embankments on soft soils
Author: Krenn, Harald
ISNI:       0000 0004 2668 3997
Awarding Body: University of Strathclyde
Current Institution: University of Strathclyde
Date of Award: 2008
Availability of Full Text:
Access from EThOS:
Access from Institution:
The design of embankments on soft soils requires a reliable estimate of deformations and stability of the embankment. Natural soft soils are structured materials, and as a consequence they exhibit anisotropy in their stress-strain-strength behaviour. The complex nature of soft soil makes it very difficult for designers to estimate deformations during construction and over time. The properties of very soft clays, silts and organic soils can be improved with deep mixing. Conventional design methods are very limited and do not account for the complex stress-strain-strength behaviour of the soft soil and/or the deep mixed soil. Numerical techniques, such as the finite element method provide a powerful tool, given the complex stress-strain-strength behaviour of the soft soil and/or the deep mixed material can be taken into account using advanced constitutive models. The aim of the thesis is to investigate through 2D and 3D numerical simulations using advanced constitutive models the behaviour of embankments constructed on soft clays. In addition to embankments constructed on natural soils, embankments on deep mixed columns are studied. Simulations investigate the effect of anisotropy, apparent interparticle bonding and destructuration on the predicted response. It was found that ignoring anisotropy and destructuration leads to underprediction of surface settlements and horizontal displacements. However, although the effect of anisotropy was more pronounced than the effect of destructuration, the latter is needed to represent the measured remoulded and natural undrained strength in time. Constitutive models with a hyperbolic stress-strain relationship give a good representation of the non-linear behaviour of deep mixed material. 3D simulations of embankments on deep mixed columns showed that with increasing column spacing, differential settlements occur between column and soil. The results furthermore demonstrate that floating columns can be very effective in settlement reduction.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral